#include <iostream>
using namespace std;


struct TreeNode 
{
    int val;
    TreeNode *left;
    TreeNode *right;
    TreeNode() : val(0), left(nullptr), right(nullptr) {}
    TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
    TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
};
 
class Solution {
    int count = 0;
    int ret = 0;
public:
    int kthSmallest(TreeNode* root, int k)
    {
        count = k;
        dfs(root);
        return ret;
    }

    void dfs(TreeNode* root)
    {
        if (root == nullptr || count <= 0)
            return;

        dfs(root->left);
        count--;
        if (count == 0)
            ret = root->val;
        dfs(root->right);
    }
};

int main()
{

    return 0;
}